Components for artificial joints

ABSTRACT

A component of an artificial joint according to an exemplary aspect of the present disclosure includes, inter alia, a hollow tube including bone ingrowth material. Further, the hollow tube is selectively expandable. The bone ingrowth material allows the component to become biologically fixed to adjacent bone. Further, expansion of the hollow tube increases friction between the hollow tube and the adjacent bone, which increases stability.

BACKGROUND

This disclosure relates to components for artificial joints and, moreparticularly, to artificial femoral and tibial components for use duringunicondylar or total knee arthroplasty procedures.

A total knee arthroplasty, also known as total knee replacement, is asurgical procedure in which parts of the knee joint are replaced withartificial components (sometimes referred to as prostheses). In atypical total knee arthroplasty procedure, an artificial femoralcomponent is attached to the femur, an artificial tibial component isattached to the tibia, and a spacer is provided between the femoral andtibial components.

SUMMARY

This disclosure describes components for artificial joints. Thecomponents can be used during joint replacement procedures. For example,the components could be artificial femoral or tibial components for useduring unicondylar or total knee arthroplasty procedures.

An artificial joint component according to an exemplary aspect of thepresent disclosure includes, inter alia, a hollow tube including boneingrowth material. Further, the hollow tube is selectively expandable.The bone ingrowth material allows the component to become biologicallyfixed to adjacent bone. Further, expansion of the hollow tube increasesfriction between the hollow tube and the adjacent bone, which increasesstability.

In a further embodiment, the component includes an opening aligned withthe hollow tube, and a plug receivable in the opening. The plug isconfigured to engage an interior of the hollow tube to expand the hollowtube. The hollow tube may, in some embodiments, include a slit alongsubstantially the entire length thereof to allow for expansion.

An artificial knee according to an exemplary aspect of the presentdisclosure includes, inter alia, an artificial femoral componentincluding a hollow tube having bone ingrowth material, and an artificialtibial component including a hollow tube having bone ingrowth material.Further, the hollow tube of one of the artificial femoral component andthe artificial tibial component is selectively expandable. Additionally,the artificial knee includes a spacer located between the artificialfemoral component and the artificial tibial component.

In a further embodiment, the artificial femoral component furtherincludes an anterior surface providing an articulating surface relativeto the spacer. The artificial femoral component also includes aposterior surface substantially covered by bone ingrowth material.Further, the hollow tube of the artificial femoral component projects ina posterior direction from the posterior surface.

A method according to an exemplary aspect of the present disclosureincludes, inter alia, expanding a hollow tube of a component of anartificial joint, the hollow tube including bone ingrowth material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example artificial joint. In this example, theartificial joint is an artificial knee.

FIG. 2A is a posterior-perspective view of an example artificial femoralcomponent.

FIG. 2B is a posterior view of the artificial femoral component of FIG.2A.

FIG. 2C is a cross-sectional view of the artificial femoral componenttaken along line 2C-2C of FIG. 2B.

FIG. 2D is a close-up view of the encircled area in FIG. 2C, andillustrates a hollow tube with bone ingrowth material on a solidbacking.

FIG. 2E is a close-up view of the encircled area of FIG. 2C, andillustrates a hollow tube made entirely of bone ingrowth material.

FIG. 3A is a superior-perspective view of an example artificial tibialcomponent.

FIG. 3B is a superior-perspective view of the artificial tibialcomponent of FIG. 3A, and illustrates first and second plugs insertedinto respective openings.

FIG. 3C is a side view of the artificial tibial component of FIG. 3A.

FIG. 4A is a cross-sectional view of the artificial tibial componenttaken along line 4A-4A of FIG. 3A.

FIG. 4B is a cross-sectional view of the artificial tibial componenttaken along line 4B-4B of FIG. 3B.

FIG. 4C is a cross-sectional, side view of the artificial tibialcomponent illustrating a second example plug type.

FIG. 4D is a cross-sectional, side view of the artificial tibialcomponent illustrating a third example plug type.

FIG. 5 is a flow chart representative of an example method according tothis disclosure.

DETAILED DESCRIPTION

This disclosure describes components for artificial joints. Thecomponents can be used during joint replacement procedures. For example,the components could be artificial femoral or tibial components for useduring unicondylar or total knee arthroplasty procedures.

In some embodiments, a component of an artificial joint includes ahollow tube having bone ingrowth material. The hollow tube includes boneingrowth material adapted to provide stability to the component viabiological fixation. The hollow tube is also selectively expandable.Expansion of the hollow tube increases friction between the hollow tubeand the adjacent bone, which further increases fixation. The artificialcomponents of the present disclosure are “cementless,” i.e., they can befixed to bone without the use of bone cement.

In a further embodiment, the component includes an opening aligned withthe hollow tube, and a plug receivable in the opening. The plug isconfigured to engage an interior of the hollow tube to expand the hollowtube.

In a further embodiment, the opening and the plug are threaded.

In a further embodiment, the plug includes a threaded shank projectingbeyond the hollow tube and configured to engage bone.

In a further embodiment, the plug includes a flared portion distal ofthe threads, the flared portion configured to engage an interior of thehollow tube.

In a further embodiment, the hollow tube includes at least one slitalong a substantially an entire length thereof.

In a further embodiment, the hollow tube includes a layer of boneingrowth material provided on a substantially solid backing material.

In a further embodiment, the hollow tube consists of bone ingrowthmaterial.

In a further embodiment, the hollow tube is substantially cylindricaland defines an interior cavity.

In a further embodiment, the component is a tibial tray, and wherein thehollow tube projects from an inferior surface of the tibial tray.

An artificial knee according to an exemplary aspect of the presentdisclosure includes, inter alia, an artificial femoral componentincluding a hollow tube having bone ingrowth material, and an artificialtibial component including a hollow tube having bone ingrowth material.Further, the hollow tube of one of the artificial femoral component andthe artificial tibial component is selectively expandable. Additionally,the artificial knee includes a spacer located between the artificialfemoral component and the artificial tibial component.

In a further embodiment, the artificial femoral component furtherincludes an anterior surface comprising an articulating surface relativeto the spacer. The artificial femoral component also includes aposterior surface substantially covered by bone ingrowth material.Further, the hollow tube of the artificial femoral component projects ina posterior direction from the posterior surface.

In a further embodiment, the artificial femoral component includes twohollow tubes, and each of the hollow tubes of the artificial femoralcomponent includes bone ingrowth material.

In a further embodiment, the artificial tibial component furtherincludes an opening aligned with the hollow tube of the artificialtibial component, and a plug receivable in the opening. The plug isconfigured to engage an interior of the hollow tube to expand the hollowtube.

In a further embodiment, the opening and the plug are threaded.

In a further embodiment, the plug includes one of (1) a threaded shankprojecting beyond the hollow tube and configured to engage bone, and (2)a flared portion distal of the threads and configured to engage thehollow tube.

In a further embodiment, the hollow tube of the artificial tibialcomponent includes at least one slit along substantially the entirelength thereof.

A method according to an exemplary aspect of the present disclosureincludes, inter alia, expanding a hollow tube of a component of anartificial joint, the hollow tube including bone ingrowth material.

In a further embodiment, the method further includes forming a hole inbone and inserting the hollow tube into the hole. The hollow tube issized to substantially correspond to the size of the hole.

In a further embodiment, the hollow tube is expanded as a plug isinserted into an opening of the component.

FIG. 1 illustrates an example artificial joint 20. In this non-limitingexample, the artificial joint 20 is an artificial knee. While anartificial knee is specifically mentioned herein, this disclosure is notlimited to artificial knees and can have applications in other parts ofthe body.

The artificial joint 20 includes an artificial femoral component 22connected to a femur 24, an artificial tibial component 26 connected toa tibia 28, and a spacer 30 arranged between the artificial femoralcomponent 22 and the artificial tibial component 26. In thisnon-limiting example, the artificial femoral and tibial components 22,26 are made of metallic materials, and the spacer 30 is made of aplastic material. However, this disclosure is not limited to theseparticular materials.

In a non-limiting example, the artificial tibial component 26 is atibial tray having a base plate 32. A superior, or top, portion of thebase plate 32 is configured to support the spacer 30, and the inferior,or bottom, of the base plate 32 is configured to mate with a tibialplateau cut 33. The “superior” and “inferior” directions are labeled inthe figures for purposes of explanation only.

The artificial femoral component 22 includes an anterior surface 34,which provides an articulating surface that engages the spacer 30. Theartificial femoral component 22 further includes a posterior surface 36configured to mate with cuts of the femur 24.

FIG. 2A illustrates an example artificial femoral component 22 from aposterior perspective. The “anterior” and “posterior” directions arelabeled across the figures for purposes of explanation only. In thisexample, the posterior surface 36 of the artificial component 22 hasproximal and distal planar surfaces 38, 40, and a planar chamfer surface42 extending between the proximal and distal planar surfaces 38, 40. Theplanar surfaces 38, 40, 42 correspond to cuts made in the femur 24.

In this example, the posterior surface 36 is substantially covered witha layer 44 of bone ingrowth material. The bone ingrowth material isrelatively porous, which allows bone to grow into the layer 44. The boneingrowth material may be provided by a metal foam material in someexamples. As bone grows into the layer 44, the artificial femoralcomponent 22 becomes biologically fixed to the femur 24. The layer 44 ofbone ingrowth material may be fused to the posterior side of the femoralcomponent 22. In another non-limiting example, the layer 44 is providedusing a deposition coating process.

To further increase stability, the artificial femoral component 22includes first and second hollow tubes 46, 48 projecting from theposterior surface 36 in a posterior direction. In this example, thefirst hollow tube 46 projects from the surface 38, and the second hollowtube 48 projects from the surface 42. Further, the first and secondhollow tubes 46, 48 are substantially cylindrical and have a hollowinterior providing respective cavities 50, 52 therein. While two hollowtubes are illustrated in this example, this disclosure extends toartificial femoral components having one or more hollow tubes.

With reference to FIG. 2B, the first hollow tube 46 is arranged about afirst axis A₁, and the second hollow tube 48 is arranged around about asecond axis A₂. In this example, the axes A₁, A₂ are spaced-apart fromone another in the medial and lateral directions. The “medial” and“lateral” directions are shown in FIG. 2B for purposes of explanationonly. Further, as seen in FIG. 2C, the first and second axes A₁, A₂ areinclined such that they are substantially parallel to one another.Additionally, in this example, the first hollow tube 46 has a length L₁,which is shorter than a length L₂ of the second hollow tube 48.

The first and second hollow tubes 46, 48 are configured such that bonemay grow into the first and second cavities 50, 52, which increases thesurface area of the tubes 46, 48 exposed to bone, which in turnincreases fixation. But further, bone may grow into at least a portionof the first and second hollow tubes 46, 48 themselves.

In one example, as illustrated in FIG. 2D, the first hollow tube 46 isprovided by a solid backing material 54 supporting an outer layer 56 ofbone ingrowth material. Alternatively, as illustrated in FIG. 2E, thehollow tube 46 may be provided entirely by bone ingrowth material 58.These arrangements allow bone to grow into the hollow tubes 46, 48,which increases stability and reliability of the artificial femoralcomponent 22. While the first hollow tube 46 is illustrated in FIGS.2D-2E, it should be understood that the second hollow tube 48 could bearranged similarly.

FIGS. 3A-3C illustrate an example artificial tibial component 26 from asuperior-perspective view. In this example, the base plate 32 of thetibial component 26 includes a rim 68 extending around a perimeter andestablishing a pocket 70 therein. The pocket 70 receives a portion ofthe spacer 30. In this example, the pocket 70 includes first and secondthreaded openings 72, 74. The first and second threaded openings 72, 74are configured to receive first and second threaded plugs 76, 78, whichare configured to expand respective first and second hollow tubes 80, 82(FIG. 3C) aligned with the first and second threaded openings 72, 74, aswill be discussed below. While reference is made to “threaded” openingsand plugs, this disclosure extends to non-threaded arrangements.Further, while two sets of openings, plugs, and tubes are illustrated,this disclosure extends to artificial tibial components with one or moreof such sets. Additionally, while the artificial tibial component 26 isshown having expandable hollow tubes, the artificial femoral component22 could also include expandable hollow tubes. While the hollow tube maybe expandable in an embodiment, in another embodiment the hollow tubesare not expandable.

In this example, an inferior surface 84 of the tibial component 26 issubstantially covered by a layer 86 of bone ingrowth material. The boneingrowth material may be the same type of bone ingrowth material asdescribed above relative to the artificial femoral component 22, and maybe applied in the same way. Further, the first and second hollow tubes80, 82 are also provided with bone ingrowth material on a solid backing,or are alternatively provided entirely by bone ingrowth material, as inthe examples of FIGS. 2D and 2E, respectively.

In this example, the first and second hollow tubes 80, 82 are providedalong first and second axes A₃, A₄. The first and second axes A₃, A₄ aresubstantially perpendicular to the inferior surface 84 of the tibialcomponent 26. The first and second hollow tubes 80, 82 project in theinferior direction from the inferior surface 84 by a length L₃.

The first and second hollow tubes 80, 82 in this example are providedwith one or more slits 88, 90 along substantially the entire length L₃of the first and second hollow tubes 80, 82. The slits 88, 90 allowexpansion of the first and second hollow tubes 80, 82 in the radiallyoutward directions R₁, R₂ relative to the respective axes A₃, A₄.

In one example, the first and second hollow tubes 80, 82 are selectivelyexpandable in the radially outward directions R₁, R₂ upon insertion ofthe first and second plugs 76, 78 into the first and second threadedopenings 72, 74. Expansion of the first and second hollow tubes 80, 82in the radially outward directions R₁, R₂ increases the friction betweenthe first and second hollow tubes 80, 82 and the corresponding tibialbone, which increases stability of the artificial tibial component 26.

FIG. 4A is a cross-sectional view taken along line 4A-4A from FIG. 3A.FIG. 4A illustrates the detail of the first threaded opening 72 and thefirst hollow tube 80. In this example, the first threaded opening 72includes a threaded portion 92 having a first diameter D₁ adjacent thepocket 70. The diameter of the first threaded opening 72 graduallytapers down to a second diameter D₂, which is less than the firstdiameter D₁. The threaded portion 92 terminates at a point inferior to(i.e., beneath) the inferior surface 84 and within the interior of thefirst hollow tube 80, in this example.

With reference to FIG. 5, an example method 110 of installing theartificial tibial component 22 is described. In the method 110, openingsare formed in a bone, such as a tibial bone, at 112. Next, the first andsecond hollow tubes 80, 82 are received in those openings, at 114.Finally, the first and second hollow tubes 80, 82, are expanded, at 116.In one example, the first and second hollow tubes 80, 82 are expanded asthe first and second threaded plugs 76, 78 are inserted into openings72, 74.

Specifically, with reference to FIG. 4B, the first threaded plug 76 isinserted into the first threaded opening 72 by way of a driver, forexample. In this example, the first threaded plug 76 is inserted in afirst insertion direction I₁, from the superior side of the artificialtibial component 22 toward the inferior side of the artificial tibialcomponent 22. The first threaded plug 76 is sized such that its outerdiameter substantially corresponds to the first diameter D₁. As thefirst threaded plug 76 moves toward the second diameter D₂ of the firstthreaded opening 72, the first threaded plug 76 expands the first hollowtube 80 in the radially outward direction R₁ relative to the first axisA₃.

FIGS. 4C and 4D illustrate alternative plug configurations. FIG. 4Cillustrates a second type of plug 94 having a threaded portion 96similar to the first plug 76. Distal of the threaded portion 96, theplug 94 includes a flared portion 98. The flared portion 98 tapers froma maximum dimension at the distal end 100 of the plug 94 to the threadedportion 96. In this example, the plug 94 may be inserted in a seconddirection I₂ opposite direction I₁. The flared portion 98 is sized toabut the interior of the first hollow tube 80 and expand the firsthollow tube 80 in the radially outward direction R₁.

With reference to FIG. 4D, a third type of plug 102 includes a firstthreaded portion 104 sized similarly to the threads of the firstthreaded plug 76. The plug 102 further includes a shank portion 106configured to project beyond the inferior end of the first hollow tube80 and including a second threaded portion 108 for engaging bone. Theshank portion 106 has an outer dimension smaller than the first threadedportion 104. The first threaded portion 104 serves to expand the firsthollow tube 80 in substantially the same way as the plug 76, while thesecond threaded portion 108 provides additional fixation relative to thetibial bone.

It should be understood that terms such as “superior,” “inferior,”“anterior,” “posterior,” “medial,” “lateral,” etc., are used herein forpurposes of explanation, and should not be considered otherwiselimiting. Terms such as “generally,” “substantially,” and “about” arenot intended to be boundaryless terms, and should be interpretedconsistent with the way one skilled in the art would interpret thoseterms.

Although the different examples have the specific components shown inthe illustrations, embodiments of this disclosure are not limited tothose particular combinations. It is possible to use some of thecomponents or features from one of the examples in combination withfeatures or components from another one of the examples.

One of ordinary skill in this art would understand that theabove-described embodiments are exemplary and non-limiting. That is,modifications of this disclosure would come within the scope of theclaims. Accordingly, the following claims should be studied to determinetheir true scope and content.

1-10. (canceled)
 11. An artificial knee, comprising: an artificialfemoral component including a hollow tube having bone ingrowth material;an artificial tibial component including a hollow tube having boneingrowth material, wherein the hollow tube of one of the artificialfemoral component and the artificial tibial component is selectivelyexpandable; and a spacer located between the artificial femoralcomponent and the artificial tibial component.
 12. The artificial kneeas recited in claim 11, wherein the artificial femoral component furthercomprises: an anterior surface comprising an articulating surfacerelative to the spacer; and a posterior surface substantially covered bybone ingrowth material, wherein the hollow tube of the artificialfemoral component projects in a posterior direction from the posteriorsurface.
 13. The artificial knee as recited in claim 12, wherein theartificial femoral component includes two hollow tubes, each of thehollow tubes of the artificial femoral component including bone ingrowthmaterial.
 14. The artificial knee as recited in claim 11, wherein theartificial tibial component further comprises: an opening aligned withthe hollow tube of the artificial tibial component; and a plugreceivable in the opening, wherein the plug is configured to engage aninterior of the hollow tube to expand the hollow tube.
 15. Theartificial knee as recited in claim 14, wherein the opening and the plugare threaded.
 16. The artificial knee as recited in claim 15, whereinthe plug includes one of (1) a threaded shank projecting beyond thehollow tube and configured to engage bone, and (2) a flared portiondistal of the threads and configured to engage the hollow tube.
 17. Theartificial knee as recited in claim 11, wherein the hollow tube of theartificial tibial component includes at least one slit alongsubstantially the entire length thereof. 18-20. (canceled)